1. Technical Field of the Invention
The present invention relates to a control device and method used for controlling controlled objects, especially those which are continuously operated.
2. Background Art
Generally, in control devices, the various control parameters are set depending on the operating characteristics of the controlled objects, that is, the response characteristics of observed quantities which are outputted from the controlled objects with respect to operated quantities inputted from the control device. The operated quantities are generated by applying a standard procedure to the observed quantities based on the various control parameters set in this manner, by means of a predetermined control logic.
However, due to changes (modifications) in the operating characteristics of the controlled objects, changes in the noise environment, or restrictions on the input/output signals of the controlled objects, there are cases wherein modifications to the control parameters or modifications in the control logic become necessary. Conventionally, in these cases, since the control device must be stopped and the hardware or software structure changed, the controlled objects must be halted over a standard period of time. For example, in the case of the control of various chemical plants, it is impossible to halt the plants in order to modify the control structure.